Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

# The Height of Mercury Column in a Barometer in a Calcutta Laboratory Was Recorded to Be 75 Cm. Calculate this Pressure in Si and Cgs Units - Physics

Sum

The height of mercury column in a barometer in a Calcutta laboratory was recorded to be 75 cm. Calculate this pressure in SI and CGS units using the following data : Specific gravity of mercury = $13 \cdot 6$ , Density of $\text{ water} = {10}^3 kg/ m^3 , g = 9 \cdot 8 m/ s^2$ at Calcutta. Pressure
= hpg in usual symbols.

#### Solution

Height, h = 75 cm = 0.75 m
Density of mercury = 13600 kg/m3
g = 9.8 m/s2

In SI units, pressure = hρg = 0.75 × 13600 × 9.8 = 10 × 104 N/m2 (approximately)

In CGS units, pressure = 10 × 104 N/m2

$= \frac{10 \times {10}^4 \times {10}^5 \text{dyne}}{{10}^4 {\text{cm}}^2} = 10 \times {10}^5 \text{dyne}/ {\text{cm}}^2$

Concept: What is Physics?
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 1
Chapter 1 Introduction to Physics
Exercise | Q 10 | Page 10
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